The study of the effects of social mobility has long interested researchers. Nevertheless, most empirical analyses seem unsatisfactory due to the difficulty of defining a model that correctly expresses, in technical and substantial terms, the effect of social origins and destinations. This article introduces a strategy of analysis of mobility effects: the use of diagonal mobility models (developed by M.E. Sobel). Particularly, diagonal mobility models are applied to the study of the influence of social origins and destinations on fertility choices in Italy. The intent of this article is thus twofold: it highlights characteristics and potentialities of analysing diagonal mobility models; it offers a contribution for a better understanding of reproductive behaviour in Italy.